This may be related to the antitheft system. The system is
known for turning off the starter and/or injectors when it fails.
Normally when the injectors are turned off, the car will run for a
second or two, and then stall. When it's the security locked out
starter, you won't even hear a click when you turn the key. Is
there a light on the dash that says SECURITY or a picture of a
car with a lock through it? This is a common problem worth
looking into. http://www.diy-gm-security.com/ &
http://newrockies.com/